Portable communication and computing devices such as smartphones, mobile phones, tablets etc. are compact devices which are powered from rechargeable battery sources. The compact dimensions and battery source put severe constraints on the maximum acceptable dimensions and power consumption of microphones and microphone amplification circuit utilized in such portable communication devices.
US 2011/0051954 A1 discloses a signal conditioner for a capacitive transducer. The signal conditioner includes a differential preamplifier which includes a non-inverting input connected to a microphone transducer output and a separate inverting input connected to the output of a feedback path. The feedback path includes a digital-to-analogue converter and extends from an output of an analogue-to-digital converter to the inverting input of the preamplifier.
However, there exists a continued need to improve the sound quality and robustness of microphone assemblies for example by accurately controlling the frequency response and reducing or eliminating overload distortion of signal processing circuits like microphone preamplifiers at high sound pressure levels. The overload and distortion problems are often caused by saturation and non-linearity of active amplification elements like transistors of the signal processing circuits.